EP0645533B1 - Luft-Kraftstoffverhältnis-Regeleinrichtung für eine Bremskraftmaschine - Google Patents

Luft-Kraftstoffverhältnis-Regeleinrichtung für eine Bremskraftmaschine Download PDF

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Publication number
EP0645533B1
EP0645533B1 EP94306106A EP94306106A EP0645533B1 EP 0645533 B1 EP0645533 B1 EP 0645533B1 EP 94306106 A EP94306106 A EP 94306106A EP 94306106 A EP94306106 A EP 94306106A EP 0645533 B1 EP0645533 B1 EP 0645533B1
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Prior art keywords
ratio
signal
engine
downstream
upstream
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English (en)
French (fr)
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EP0645533A1 (de
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Tri T. Truong
Daniel V. Orzel
Glenn A. Zimlich
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Ford Werke GmbH
Ford France SA
Ford Motor Co Ltd
Ford Motor Co
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Ford Werke GmbH
Ford France SA
Ford Motor Co Ltd
Ford Motor Co
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N11/00—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity
    • F01N11/007—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity the diagnostic devices measuring oxygen or air concentration downstream of the exhaust apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2550/00—Monitoring or diagnosing the deterioration of exhaust systems
    • F01N2550/02—Catalytic activity of catalytic converters
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/40—Engine management systems

Definitions

  • the invention relates to controlling engine air/fuel ratio while concurrently monitoring the efficiency of a catalytic converter coupled to an engine exhaust.
  • converter degradation is indicated by comparing a ratio of downstream to upstream sensor switching frequency to a reference value while the vehicle is operating over a predetermined time period.
  • a ratio of downstream to upstream sensor amplitude is compared during the predetermined time period.
  • USP 5119628 disclosed monitoring the ratio of reversal of an upstream and downstream oxygen sensor of an internal combustion engine having an exhaust catalyst, so as to determine catalyst deterioration. The test is performed each time the engine has completed a predetermined operation.
  • An object of the invention herein is to concurrently provide engine air/fuel feedback control and monitoring of converter efficiency with less variation in monitoring results than heretofore possible.
  • the above object and advantages are achieved, and problems of prior approaches overcome, by providing both a system and method for controlling engine air/fuel ratio and concurrently monitoring efficiency of a catalytic converter positioned in the engine exhaust.
  • the method for controlling engine air/fuel ratio and concurrently monitoring efficiency of a catalytic converter positioned in the engine exhaust comprises the steps of:
  • the weighted average of the monitoring ratio is reset to the monitoring ratio after the monitoring ratio exceeds the weighted average by a preselected amount.
  • the above aspect of the invention is applicable to any form of ratio comparison such as frequency ratio, amplitude ratio, or area ratio.
  • An advantage of the above aspect of the invention is that variations in operator habits over a test cycle should not result in an erroneous failure.
  • An additional advantage is that use of the weighted average will not mask a significant and sudden change in converter operation because the weighted average is reset to the monitoring ratio when such a sudden change occurs.
  • Controller 10 is shown in the block diagram of Figure 1 as a conventional microcomputer including: microprocessor unit 12; input ports 14; output ports 16; read-only memory 18; random access memory 20; keep-alive memory 22; and a conventional data bus. Controller 10 is shown receiving various signals from sensors coupled to engine 28 including: measurement of inducted mass airflow (MAF) from mass airflow sensor 32; engine coolant temperature (T) from temperature sensor 40; indication of engine speed (rpm) from tachometer 42; output signal FEGO from conventional exhaust gas oxygen sensor 44, positioned upstream of catalytic converter 50; and signal REGO from another conventional exhaust gas oxygen sensor (52) positioned downstream of catalytic converter 50.
  • MAF inducted mass airflow
  • T engine coolant temperature
  • rpm engine speed
  • tachometer 42 output signal FEGO from conventional exhaust gas oxygen sensor 44, positioned upstream of catalytic converter 50
  • signal REGO from another conventional exhaust gas oxygen sensor (52) positioned downstream of catalytic converter 50.
  • Intake manifold 58 of engine 28 is shown coupled to throttle body 60 having primary throttle plate 62 positioned therein. Throttle body 60 is also shown having fuel injector 76 coupled thereto for delivering liquid fuel in proportion to the pulse width of signal fpw from controller 10. Fuel is delivered to fuel injector 76 by a conventional fuel system including fuel tank 80, fuel pump 82, and fuel rail 84. Other engine components and systems such as an ignition system are not shown because they are well known to those skilled in the art.
  • closed-loop air/fuel control is commenced (step 104) when engine temperature is within a predetermined range, the engine has been operating for at least a preselected time, and throttle position is within a preselected range.
  • signal REGO is read (step 108) and subsequently processed in a proportional plus integral controller as described below.
  • step 126 signal REGO is multiplied by gain constant GI and the resulting product added to products previously accumulated (GI * REGO i-1 ) in step 128. Stated another way, signal REGO is integrated each sample period (i) in steps determined by gain constant GI. During step 132, signal REGO is also multiplied by proportional gain GP. The integral value from step 128 is added to the proportional value from step 132 during addition step 134 to generate fuel trim signal FT.
  • an open-loop fuel quantity is first determined by dividing measurement of inducted mass airflow (MAF) by desired air/fuel ratio AFd which is typically the stoichiometric value for gasoline combustion.
  • This open-loop fuel charge is then adjusted, in this example divided, by feedback variable FV which is generated as described below with respect to steps 160-178 shown in Figure 3.
  • step 160 After determining that closed-loop control is desired (step 160), by monitoring engine operating conditions such as those previously described herein with reference to step 104 in Figure 2, signal FEGO is read during step 162. Signal FEGO is then trimmed (in this example by addition) with trim signal FT which is transferred from the routine previously described with reference to Figure 2 to generate trimmed signal TS.
  • the product of integral gain value KI times trimmed signal TS (step 170) is generated and added to the previously accumulated products (step 172). That is, trimmed signal TS is integrated in steps determined by gain constant KI each sample period (i) during step 172.
  • a product of proportional gain KP times trimmed signal TS (step 176) is then added to the integration of KI * TS during step 178 to generate feedback variable FV.
  • the process described above with particular reference to Figure 3 may be performed by biasing signal FV, rather than trimming signal FEGO, with fuel trim signal FT.
  • two proportional gain constants KP 1 and KP 2 ) are used to advantage.
  • Proportional gain KP 1 multiplies signal FEGO when it switches from a lean to a rich indicating state and proportional gain KP 2 multiplies signal FEGO when it switches from a rich to a lean state.
  • Proportional term KP 1 is incremented when fuel trim signal FT indicates a lean bias is desired and proportional term KP 1 is decreased (or KP 2 incremented) when a rich bias is desired by fuel trim signal FT.
  • step 198 and step 200 signal FV is band pass filtered and then rectified.
  • a graphical representation of signal FV during typical engine operation is show in Figure 5A and its filtered output shown in Figure 5B (before rectification).
  • signal REGO is band pass filtered, and the filtered output rectified (see steps 204 and 206 in Figure 4A).
  • a graphical representation of signal REGO during typical engine operation is shown in Figure 6A, and the signal output after band pass filtering is shown in Figure 6B (before rectification). It is noted that the band pass filter operation facilitates the subsequent operation of computing area under the signal curves (i.e., integration).
  • initial engine conditions are checked during step 210 before entering the test cycle described below. More specifically, the test cycle is entered when engine temperature (T) is within a predetermined range, a predetermined time elapsed since the engine was started, and the closed loop air/fuel control has been operable for a preselected time.
  • T engine temperature
  • the inducted air flow range in which engine 28 is operating is determined. These ranges are described as range (1), range (2)..., and range (n), for this example wherein "n" inducted air flow ranges are used to advantage. Assuming engine 28 is operating within air flow range (1), the transition between states of signal FV are counted to generate count signal CFV 1 . While engine operation remains within airflow range (1), count CFV 1 is incremental each transition of signal FV until count CFV 1 is equal to maximum count CFV 1max (steps 232 and 236).
  • step 226 count CFV n is incremental each transition of feedback variable FV until it reaches maximum count CFV nmax (steps 252 and 256).
  • step 274 a converter test cycle or period is completed when engine 28 has operated for a predetermined period in each of "n" airflow ranges. Each of these predetermined periods is generated when feedback variable FV has completed a preselected number of transitions or cycles.
  • the area under the curve formed by signal REGO (after it is band pass filtered and rectified) is computed during steps 268 and 270. More specifically, during each background loop of controller 10, the area under the REGO curve is computed during the present background loop (step 268) and added to the previously accumulated areas to generate total area AREGO t (step 270).
  • step 274 a determination is made that the test cycle or period has been completed when the count in transitions of feedback variable FV for each airflow range (CFV 1 ...CFV n ) has reached its respective maximum value (MAX).
  • area ratio ARAT is computed by dividing the total area under the feedback variable curve (AFV t ) into the area under the REGO curve (AREGO t ) during step 278. Variables CFV 1 ...CFV n , AFV t, and AREGO t are also reset (step 280).
  • area ratio flag ARAT is set (step 284).
  • step 298 initial engine conditions are checked (see step 210 in Figure 4A) before entering the test cycle described below.
  • steps 300, 304, and 306 the inducted airflow range in which engine 28 operating is determined. These ranges are described as range (1), range (2), and range (n) for this example wherein "n" inducted airflow ranges are used to advantage.
  • transitions between states of signal FEGO are counted to generate count signal CF 1 .
  • test period (n) when engine 28 is operating within airflow range (n) as shown in step 306, test period (n), count CF n , and count CR n are generated as shown in steps 332, 336, and 338.
  • step 350 a determination is made as to whether engine 28 has operated in all airflow ranges (i ⁇ n) for the required minimum duration or test period. Stated another way, step 350 determines when each count of transitions in signal FEGOS (CF 1 , CF 2 , ⁇ CF n ) have reached their respective maximum values (CF 1max , CF 2max , ⁇ CF nmax ). Each count (CF 1max ⁇ CF nmax ) of transitions in signal FEGOS is then summed in step 354 to generate total count CF t .
  • Total count CR t is generated in step 356 by summing each count (CR 1 ⁇ CR n ) for each airflow range during the test period. A ratio of total count CR t to total count CF t is then calculated during step 360 and all counts subsequently reset in step 362. If the calculated ratio is greater than a preselected reference ratio (RAT f ) a frequency ratio flag is set (steps 366 and 370) indicating that converter efficiency has degraded below a preselected limit.
  • RAT f preselected reference ratio
  • Steps 398-456 are processed in a manner similar to that previously described herein with respect to corresponding steps 198-256 shown in Figures 4A-4B.
  • step 398 and step 400 signal FV is band pass filtered and then rectified.
  • signal REGO is band pass filtered, and the filtered output rectified (see steps 404 and 406 in Figure 6A). Initial engine conditions are checked during step 410 before entering the test cycle described below.
  • the inducted airflow range in which engine 28 is operating is determined during steps 420, 424, and 426.
  • the transition between states of signal FV are counted to generate count signal CFV 1 .
  • Each transition of signal FV, count CFV 1 is incremented until it reaches its maximum count CFV 1max (steps 432 and 436).
  • the same procedure is followed when engine 28 is operating within airflow range (n) as shown in steps 426, 452, and 456.
  • This portion of the converter test cycle or period is completed when engine 28 has operated in each of "n" airflow ranges during a preselected number of transitions in signal FV.
  • a similar result may also be achieved by counting transitions in signal FEGO in place of transitions in signal FV.
  • peak amplitude PARGO 1i of signal REGO is stored during each cycle (i) of signal FV in step 460.
  • peak-to-peak signal PPREGO 1i is calculated by adding peak amplitude PARGO 1i during the present (i) cycle to the peak amplitude during the previous (i -1) cycle.
  • Total peak amplitude PPREGO 1t for airflow range (1) is calculated by adding peak-to-peak amplitude PPREGO 1i from each FV cycle.
  • peak amplitude PAFV 1i of feedback variable FV is stored during each cycle (i) of signal FV.
  • Peak-to-peak amplitude PPFV 1i is calculated in step 474 by adding peak amplitude PAFV 1i during each signal FV cycle (i) to peak amplitude PAFV 1i -1 from the previous (i -1) cycle of signal FV.
  • Total peak-to-peak amplitude PPFV 1t of signal FV while engine 28 is operating in airflow range (1) is calculated in step 478 by adding peak-to-peak amplitude PPFV 1i for each cycle (i) of signal FV.
  • Total peak-to-peak amplitude PPREGO nt of signal REGO while engine 28 is operating in airflow range (n) is calculated during steps 480, 484, and 488 in a manner substantially the same as previously described herein with respect to corresponding steps 460, 464, and 468.
  • peak-to-peak signal PPFV nt is calculated during steps 490, 492, and 498 in a manner substantially the same as previously described herein with respect to corresponding steps 470, 474, and 478.
  • the test cycle for the example presented in Figures 6A-6B is completed when the count in transitions of signal FV for each airflow range (CFV 1 ...CFV n ) reaches its respective maximum value (step 500).
  • the total peak-to-peak amplitude of signal FV (PPFV T ) is calculated in step 504 by summing the total peak-to-peak amplitude of signal FV for each of the airflow ranges.
  • the total peak-to-peak amplitude of signal REGO over this test period is calculated in step 506.
  • a ratio of peak-to-peak amplitudes is calculated by dividing total peak-to-peak amplitude of signal FV into total peak-to-peak amplitude of signal REGO after completion of the test period.
  • peak-to-peak ratio PPRAT is greater than reference ratio PPRAT F (step 512)
  • the peak-to-peak ratio flag is set in step 516.
  • the appropriate monitoring ratio is selected in step 602.
  • the selected monitoring ratio may be either area ratio ARAT (from the routine shown in Figures 4A-4B), or frequency ratio FRATIO (from the routine shown in Figures 5A-5B), or peak-to-peak amplitude ratio PPRAT (from the routine shown in Figures 6A-6B).
  • a weighted average of selected ratio SRAT is computed each test cycle (p) during step 608 provided that selected ratio SRAT is within predetermined range of the ratio averaged over previous test cycles (AVRAT p-1 ) as determined in step 604.
  • predetermined range was selected as three standard deviations from the average.
  • Weighted average AVRAT p for the present test cycle is computed in step 608 by adding a percentage (shown in this example as x) of previous weighted average AVRAT p -1 to the product of the complimented percentage (1 -x) times selected ratio SRAT from the present test cycle (p). For the particular example presented herein percentage x is selected as eighty percent.
  • step 604 When selected ratio SRAT is greater than deviation from previous average ratio AVRAT p -1 (step 604), the weighted average for the present test period (AVRAT p ) is reset to selected ratio SRAT in step 612. Concurrently, the p flag for the current test period is set in step 614. The weighted averaging is thereby prevented from inadvertently masking a sudden and significant change in converter efficiency.
  • the test period is completed (step 620) when the count in transitions of feedback variable FV reaches a preselected number for each airflow range (see step 274 in Figure 4B). Weighted average AVRAT p for this test period is then compared to a preselected or predetermined value (AVRAT f ) in step 624.
  • the catalytic monitor flag is set in step 626 in response to an affirmative comparison indicating degraded converter efficiency.
  • the monitor flag (step 626) is also set when selected ratio SRAT exceeds the average ratio by for both the present and previous test cycles (see step 628).
  • a hypothetical selected ratio SRAT is shown on line 630
  • corresponding weighted average (AVRAT) is shown on line 632
  • deviation above weighted average AVRAT is shown on line 634
  • the reference ratio indicating degradation in converter efficiency is shown on line 638.
  • Selected ratio SRAT (line 630) and weighted average ratio AVRAT (line 632) are shown updated at the end of each test period (TP1-TP7).
  • selected ratio SRAT line 630
  • weighted average AVRAT is reset to selected ratio SRAT as shown at TP6 in Figure 10.
  • the reset weighted average AVRAT exceeds reference line 638 resulting in an indication of converter degradation.
  • upstream sensor 44 and downstream sensor 52 are two-state exhaust gas oxygen sensors.
  • the invention claimed herein, however, may be used to advantage with other sensors such as proportional sensors.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)

Claims (14)

  1. Verfahren zur Steuerung des Luft-Kraftstoff-Verhältnisses eines Motors und gleichzeitigen Überwachung des Wirkungsgrades eines in der Motorabgasanlage angeordneten katalytischen Wandlers (50), welches folgende Schritte aufweist:
    Steuerung der Kraftstoffabgabe an den Motor (28) in Abhängigkeit von einem Ausgang einer stromoberhalb des katalytischen Wandlers (50) angeordneten Abgas-Sauerstoffsonde (44) und einem Ausgang einer stromunterhalb des katalytischen Wandlers (50) angeordneten Abgas-Sauerstoffsonde (52);
    Einrichten einer Testperiode jedesmal dann, wenn der Motor (28) bestimmte Betriebsbedingungen erfüllt hat;
    Erzeugen eines Überwachungsverhältnisses zwischen einem durch besagte stromabwärtige Sonde (52) gewonnenen stromabwärtigen Signal und einem durch besagte stromaufwärtige Sonde (44) gewonnenen stromaufwärtigen Signal für jede der besagten Testperioden; dadurch gekennzeichnet, daß ein gewichteter Mittelwert des besagten Überwachungsverhältnisses über mehrere der besagten Testperioden bestimmt wird; und daß
    ein Schwund des Wirkungsgrades des Katalysators angezeigt wird, wenn besagter gewichteter Mittelwert des besagten Überwachungsverhältnisses einen vorbestimmten Wert überschreitet.
  2. Verfahren nach Anspruch 1, in welchem besagtes stromabwärtiges Signal aus der Häufigkeit der Schaltsprünge des Ausgangssignals der besagten stromabwärtigen Sonde gewonnen wird, und besagtes stromaufwärtiges Signal aus der Häufigkeit der Schaltsprünge des Ausgangssignals der besagten stromaufwärtigen Sonde gewonnen wird.
  3. Verfahren nach Anspruch 1, in welchem besagter gewichteter Mittelwert des besagten Überwachungsverhältnisses auf den Wert des besagten Überwachungsverhältnisses zurückgesetzt wird, nachdem besagtes Überwachungsverhältnis besagten gewichteten Mittelwert um einen vorgewählten Betrag überschritten hat.
  4. Verfahren nach Anspruch 3, worin besagter vorgewählter Betrag drei Standardabweichungen von besagtem gewichtetem Mittelwert beinhaltet.
  5. Verfahren nach Anspruch 1, in welchem besagte Anzeige von Katalysatorverschleiß auch dann erfolgt, wenn besagtes Überwachungsverhältnis besagten gewichteten Mittelwert des besagten Überwachungsverhältnisses um einen vorgegebenen Betrag eine bestimmte Anzahl von Malen überschreitet.
  6. Verfahren nach Anspruch 1, außerdem einen Schritt beinhaltend, bei dem besagte Testperiode dadurch definiert wird, daß ermittelt wird, wann der Motor den Betrieb in jedem von mehreren Ansaugluftmengenbereichen wenigstens über einen Mindestzeitraum in jedem der besagten Luftmengenbereiche abgeschlossen hat.
  7. Verfahren nach Anspruch 7, in welchem besagte Mindestdauer durch Zählen einer vorgegebenen Anzahl von Schaltsprüngen in besagtem Ausgangssignal der besagten stromaufwärtigen Abgas-Sauerstoffsonde ermittelt wird.
  8. Verfahren nach Anspruch 1, in welchem besagtes stromabwärtiges Signal aus der Amplitude des Ausganges von besagtem stromabwärtigem Geber gewonnen wird, und in welchem besagtes stromaufwärtiges Signal durch Integration des Ausganges des besagten stromaufwärtigen Gebers gewonnen wird.
  9. Verfahren nach Anspruch 1, in welchem besagtes stromabwärtiges Signal durch Integration des Ausganges von besagtem stromabwärtigem Geber gewonnen wird, und besagtes stromaufwärtiges Signal durch Integration eines gleichgerichteten Integralwertes des Ausganges von besagtem stromaufwärtigem Geber gewonnen wird.
  10. Verfahren nach Anspruch 1, außerdem einen Schritt der Bandpaßfilterung des Ausganges von besagtem stromabwärtigem Geber und des Ausganges von besagtem stromaufwärtigen Geber beinhaltend.
  11. Gerät zur Steuerung des Luft-Kraftstoff-Verhältnisses eines Motors und zur Anzeige des Wirkungsgrades eines im Abgassystem des Motors angeordneten katalytischen Wandlers, folgendes beinhaltend:
    Steuermittel zur Steuerung der an den Motor gelieferten Kraftstoffmenge in Abhängigkeit von einer Rückkopplungsvariablen, die durch Integration eines Ausgangssignals einer stromoberhalb des Katalysators angeordneten Abgas-Sauerstoffsonde und eines Ausgangssignals einer stromunterhalb des Katalysators angeordneten Abgas-Sauerstoffsonde (52) ermittelt wird;
    Mittel zur Erzeugung eines Überwachungsverhältnisses, das auf ein Verhältnis zwischen der Häufigkeit der Schaltsprünge der besagten Rückkopplungsvariablen und der Häufigkeit der Schaltsprünge im Ausgang der besagten stromabwärtigen Abgas-Sauerstoffsonde in jeder von mehreren Testperioden bezogen ist;
    Prüfmittel zur Erzeugung jeder der besagten Testperioden, wenn der Motor seinen Betrieb in jedem der besagten mehreren Ansaugluftmengenbereiche über einen vorgegebenen Zeitraum in jedem der besagten Luftmengenbereiche abgeschlossen hat;
    gekennzeichnet durch
    Mittel zur Erstellung eines Mittelwertes von besagtem Überwachungsverhältnis über mehrere der besagten Testperioden, wobei besagter Mittelwert des Überwachungsverhältnisses auf besagtes Überwachungsverhältnis zurückgesetzt wird, nachdem besagtes Überwachungsverhältnis einen vorgegebenen Wert überschritten hat; und durch
    Anzeigemittel zur Anzeige eines Wirkungsverlustes des Katalysators, wenn besagter Mittelwert des Überwachungsverhältnisses einen vorgewählten Verhältniswert übersteigt.
  12. System nach Anspruch 11, außerdem erste Filtermittel zur Bandpaßfilterung der besagten Rückkopplungsvariablen beinhaltend, sowie zweite Filtermittel zur Bandpaßfilterung des Ausgangssignals der besagten stromabwärtigen Abgas-Sauerstoffsonde.
  13. System nach Anspruch 11, in welchem besagte Steuermittel außerdem Trimmittel zur Abstimmung der besagten Rückkopplungsvariablen in Abhängigkeit von einer Integration des besagten stromabwärtigen Geberausgangs beinhalten.
  14. System nach Anspruch 11, in welchem besagte Prüfmittel den Betrieb innerhalb eines besonderen Luftmengenbereiches bestimmen, indem der Ansaugluftstrom mit einem vorgewählten Mindestwert und einem vorgegebenen Maximalwert verglichen wird, so daß der Katalysatorwirkungsgrad über einen Bereich von Abgasdurchsatzmengen bestimmt wird.
EP94306106A 1993-09-27 1994-08-18 Luft-Kraftstoffverhältnis-Regeleinrichtung für eine Bremskraftmaschine Expired - Lifetime EP0645533B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US08/126,849 US5363646A (en) 1993-09-27 1993-09-27 Engine air/fuel control system with catalytic converter monitoring
US126849 1993-09-27

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EP0645533A1 EP0645533A1 (de) 1995-03-29
EP0645533B1 true EP0645533B1 (de) 1998-05-27

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EP0645533A1 (de) 1995-03-29
DE69410561T2 (de) 1998-11-19
DE69410561D1 (de) 1998-07-02
US5363646A (en) 1994-11-15
JPH07151005A (ja) 1995-06-13

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